Tritan (Blue) Color Blindness Test

About the test

Please note that the online test cannot give you a clinical diagnosis, because standard environment (example calibrated screen) is not provided!

The task of the test is to find out the orientation of the ‘Landolt ring’, in other words to find the gap on a ‘C shape’ or to find wherw the ring is disconnected. The Colorlite test contains three series of images. The first series is red-green. Using this we can test whether you have color vision deficiency. The second image series is the purple-blue (P) and the third series is the purple-green (D). This additional two series help us to determine a diagnosis between protan and deutan type of color blindness. The number of the image, where you can not recognize the gap of the ring, represents your color discrimination ability. The bigger number means the better color discrimination. Example: 14/14 in means normal color vision, 1-5 severe, 6-10 moderate, 11-12 mild color vision deficiency in the red-green series. If the purple-blue number is bigger than the purple-green then you may have a Deutan type of color blindness, while protans have bigger number at purple-blue series. If the numbers at both series are equal (and the red-green test shows color blindness) then you may have deutan type color vision deficiency.

Scientific background of the test

The following diagrams demonstrates which colors are problematic for colorblind people. All colors in the direction of the lines might be hard to discriminate for them. The three different diagrams corresponding to the three main color vision deficiencies: protanopia (“red“ color blindness), deuteranopia (“green“ color blindness), and tritanopia (“blue“ color blindness). The lines shown above are called confusion lines. For the two types of red-green color blindness (protanopia and deuteranopia) the main problem area of colors is really in the axis between red and green. And on this side of the color space, the confusion lines are quite the same for both types. This is why they are called red-green color vision deficiency. But on the left side of the diagram you can see that they are quite different confusion lines which show the problematic colors. As you can see from the above diagrams, thewhole spectrum of colors is some way reduced for colorblind people. It is definitely not only red and green (protanopia/deuteranopia) or blue and yellow (tritanopia) which cannot be distinguished. Source: color-blindness.com

The Colorlite color vision test uses this well-known phenomenon. The colors used in the test are from the confusion lines. The red-green colors are from the color space, where the confusion lines are quite the same for both types (protan and deutan), while the purple-blue and purple-green colors are quite sensitive to differentiate them. The colors of the tritan test are in the line of the purple-red confusion lines. There is an easier explanation of the test. Example: Purple is a mix of blue and red colors of the monitor. As a consequence, if your red sensitivity is reduced (protan), the background and C shape looks similar, because the red component of the purple is reduced as well. The same for tritans just the blue sensitivity is reduced, so the background (without the blue component) will be similar to the red C shape.

The test was evaluated in a Multi-center, open, intra-individual comparative study to determine sensitivity and specificity of the test in subjects with Deutan or Protan color vision deficiencies and subjects with normal color vision as control group. Based on our research, this test (in clinical circumstances) gave a better correlation with genotypes of color vision deficiencies than the anomaloscope. Objective color vision tests should demonstrate the improvement of the color blindness correction glasses in all color segments.